Article – RecyclingToday – DEALING WITH GYPSUM – 8/6/2001
There is a lot of plasterboard produced in the US. In total, about 15 million tons of new plasterboard is produced each year (2000). California alone uses more than 10% of the nation’s total, or about 1.8 million tons per year, according to the state Waste Prevention & Market Development Division.
Most plasterboard waste—about 64%—is generated from new construction. About 12% of new construction plasterboard is wasted during installation. That figures to about two million tons per year, with over 200,000 tons in California, according to the state’s Waste Management Board in Sacramento. Demolition counts for 14% of plasterboard waste; manufacturing, 12%; and renovation 10%. That figure will vary with the construction industry and the number of natural disasters, such as earthquakes and floods, in any given year.
Although plasterboard makers like National recycle sub-standard plasterboard as part of the manufacturing process, they use little to no C&D material. “It is just not economically feasible to do it yet,” Watt explains. Even with clean construction wallboard scraps, the paper backing must be removed. Demolition scrap presents a whole host of challenges.
The exception to the landfilling of gypsum board is in Western Canada, where provincial law requires the gypsum fraction to be removed from the debris before the material goes to the landfill. Because almost all of the landfills in that area are not lined and sheetrock leaches—and because gypsum is chemically a very basic material (CaS04 2H20, or calcium sulfate dihydrate), raising the pH of the groundwater markedly when it leaches into the soil—disposal of wallboard in landfills is forbidden. In some cases noxious hydrogen sulfide gas can form. Although it is a mineral like limestone and occurs naturally in many parts of the world (in some areas, farmers even add it to their soil as a soil amendment), in other places it is undesirable in landfills. Plus, it has a low bulk density.
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